Conduit for dry chemical fire extinguisher systems



March 31, 1970 M. E. BALMES, SR 3,503,650

CONDUIT FOR DRY CHEMICAL FIRE EXTINGUISHER SYSTEMS Filed April 24, 1968 United States Patent 3,503,650 CONDUIT FOR DRY CHEMICAL FIRE EXTINGUISHER SYSTEMS Mark E. Balmes, Sr., Northbrook, Ill., assignor to General Fire Extinguisher Corporation, Northbrook, 11]., a corporation of Delaware Filed Apr. 24, 1968, Ser. No. 723,771 Int. 'Cl. B65g 53/34 U.S. Cl. 30264 4 Claims ABSTRACT OF THE DISCLOSURE An elbow joint for use in the piping system of a dry chemical fire extinguishing system in which dry chemical fire extinguisher is propelled through the piping system from a storage area to the fire area by intermixed gas pressure. The elbow has a reduced diameter venturi having a constant diameter portion extending through the bend of the elbow to prevent stream separation of the gas and dry chemical.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to fire extinguisher systems and more particularly to a direction-changing elbow for use in connection with the conduits in a dry chemical fire extinguisher system.

Prior art Dry chemical fire extinguisher systems which are used to provide a dry chemical extinguisher to a fire source from a storage point utilizing pressured gas to force the chemical through a piping system are known to the prior art. Such piping systems often require that the direction of travel of the combination intermixed gas and dry chemical be changed. Due to the centrifugal force created when a rapidly moving stream of suspended particles encounters an angular change in direction, the dry chemical is often separated from the propellant gas at the area of direction change in the piping system. There is thus presented a problem where a fully intermixed stream of dry chemical ex tinguisher and gas are caused to separate into two separate streams in a direction-changing elbow in the piping system.

This centrifugal separation of the gas and dry chemical into separately flowing streams is disadvantageous and can cause inefiicient and ineffective delivery of a proper admixture of gas and dry chemical through the discharge nozzles to a fire source. It has been known in the prior art to attempt to correct the particle separation on the downstream side of the direction-changing elbow by utilization of a sufiicient length of straight pipe as suggested in the U.S. patent to Guise et al., No. 2,708,605, or by utilization of a remixing venturi conduit placed immediately downstream of the elbow as in the U.S. patent to Ortiz, No. 3,144,276.

The patentees of these patents approach the problem from the standpoint of remixing separated streams of gas and dry chemical. This requires, in both cases, apparatus downstream of the elbow which in some instances is undesirable, where, for example, it is desired to place an elbow immediately upstream of a nozzle or a T-joint.

SUMMARY The above disadvantages are overcome by my invention which provides for a venturi in the direction-changing elbow of the piping system. In this manner, the dry chemical particles do not become separated from the gas stream when changing direction in the elbow.

In a preferred embodiment of the invention, the elbow is dimensioned externally in the conventional manner and has female threaded bores opening into either end thereof. The bores communicate to abruptly frusto-conical chambers which quickly reduce the diameter of the internal passageway through the elbow. The other ends of the frusto-conical chambers are connected to a curved constant diameter conduit area which carries the gas and dry chemical stream through the curvature of the elbow joint.

The use of my new elbow allows short-distance piping elements to be used immediately downstream of a direction change. This is most advantageous where it is desired to change direction in a single pipe fiow immediately upstream of a T-joint. It can be seen that with the prior art elbows, if the comingled gas and dry chemical are allowed to separate into two streams in the direction-changing elbow immediately prior to entry into a T-joint, that it is possible for the gas stream to be directed out one side of the T while the dry chemical stream is directed out the other side of the T. Therefore, nozzles downstream from the T would discharge, in the one instance nothing but dry chemical, and in the other instance, nothing but propellant gas.

It is therefore an object of this invention to provide an improved direction-changing elbow for use in fire extinguisher piping systems.

It is a further and more specific object of this invention to provide a new and improved direction-changing elbow designed to prevent gas and dry chemical separation in piping systems for fire extinguishers.

It is yet another and more specific object of this invention to provide a new and improved direction-changing elbow for use in fire extinguisher piping systems which has a venturi interior of the elbow to prevent stream separation of propellant gas and dry chemical extinguisher.

Other and further objects of this invention will be apparent to those skilled in this art from the following detailed description of the annexed sheet of drawings which, by way of a preferred embodiment of the invention, illustrates one example of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a sectional plan view of a prior art elbow joint illustrating separation of dry chemical and propellant gas therein.

FIGURE 2 is a sectional view of the elbow joint of this invention illustrating constantly mixed flow of dry chemical and propellant gas.

FIGURE 3 is a diagrammatic view of one form of a piping system utilizing the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIGURE 1 illustrates a typical prior art direction changing elbow used in a piping system for dry chemical fire extinguishers. The elbow 10 is of the standard curvedcylinder type having internal threads 11 at either end thereof. Externally threaded conduits 12 and 13 are threaded into the elbow 10 to form a closed right-angle conduit.

Dry chemical fire extinguisher is supplied to the conduit 12 from a storage apparatus upstream of the elbow 10. The dry chemical fire extinguisher is propelled from the storage apparatus through the piping system of which the elbow 10 is a portion by a pressured gas propellant. In order to efiectively move the extinguisher through the piping system, the dry extinguisher must be suspended in and fully intermixed with the moving stream of propellant gas. In this manner, the dry chemical extinguisher will be carried along with the gaseous stream to the fire source downstream of the elbow 10.

Prior art elbows such as the elbow which are sized to receive the conduits 12 in internal threads increase the internal diameter of the conduit system through the elbow. As an example of this, if it is assumed that the conduit 12 has an internal diameter of three-fourths of an inch, its external diameter may then be one inch. Therefore the internal diameter of the elbow 10' would be approximately one inch in order to receive the threaded end 14 of the conduit 12 therein. Therefore, the internal diameter of the conduit system as a whole increases from threefourths of an inch in the conduit 12 by a quarter of an inch to one inch in the elbow 10.

Because of the centrifugal force created by the curving of the moving stream of intermixed chemical and propellant 15 through the curvature of the elbow 10', the heavier solid particles of the dry chemical extinguisher are thrown to the outside wall of the elbow while the lighter propellant gas can flow through the elbow 10 around the inner curvature thereof. This results in a separation of the dry chemical extinguisher from the gas as is illustrated in conduit 13 of FIGURE 1. This separation can create undesirable flow interruptions at the nozzles in which the piping system terminates.

Although it is possible to remix the streams downstream of the elbow as is taught by the above-mentioned prior art, these methods have certain deficiencies, especially when it is desired to change the direction of the flow immediately upstream of the discharge nozzles or a T fitting. In addition, it is desirable to prevent gas and particle separation at any point in the system.

FIGURE 2 illustrates one embodiment of my invention which prevents particle-gas separation. In this embodiment, two conduits 17 and 18, substantially the same as the conduits 12 and 13, are threaded into the upstream 19 and downstream 20 ends of an improved elbow 21.

The elbow 21 as illustrated in FIGURE 2, has an exterior dimension substantially that of a cylinder which has been curved through a 90-degree angle. It is of course to be understood that the elbow may have a curvature other than 90 degrees. The interior of the elbow 21 is contoured to provide a venturi conduit.

The interior of the elbow 21 has an axial bore 22 therethrough. The bore is variously diarnetered having a diameter at the ends 19 and 20 sized to receive the conduits 17 and 18 therein. The ends of the conduits 17 and 18 and the ends 19 and 20 of the elbow are threaded to provide an efiective attachment of the conduits to the elbow. Axially downstream from the threaded portion 23 of the end 19 the diameter of the bore 22 is abruptly reduced to form a frusto-conical section 24 at the upstream end of the venturi. The frusto-conical section 24 reduces the diameter of the passageways approximately one-half. As an example, if it is assumed that the interior diameter of the conduit 17 is three-fourths of an inch, then the diameter at the downstream end or bottom of the frusto-conical section 24 would be three-eighths of an inch.

The diameter of the axial bore 22 then remains constant through the direction changing bend 25 in the elbow 21. The constant diameter portion 26 of the bore 22 terminates in the downstream end 20 of the elbow 21 in a second frusto-conical section 25 which increases the diameter of the bore back to the diameter necessary to receive the threaded end 26 of the conduit 18. Thus, the frustoconical sections 24 and 25 are substantially identical and elfectively change the diameter of the bore by one-half from the bases thereof.

Because the pressure in the conduit remains the same through the elbow 21 the velocity of the intermixed dry chemical extinguisher and propellant gas stream 28 increases through the venturi section 24, 25 and 26 of the elbow. The venturi, as is known from the prior art, effectively prevents stream separation of the gas and dry chemical in the elbow, thus eliminating the need for any apparatus for remixing the stream downstream of the elbow.

FIGURE 3 diagrammatically illustrates a simple form of dry chemical fire extinguisher piping system. The system 30 begins at a storage source 31 in which dry chemical and pressured gas are stored, preferably independently of each other. Exiting from the storage source 31 is a single pipe 32 which changes direction through an elbow 33 into a short length of pipe 34 immediately upstream of a T-joint 35. Two pipes 36 and 37 extend outwardly in opposite directions from the T-joint 35. The pipes 36 and 37 terminate in elbows 38 and 39' immediately upstream of discharge nozzles 40 and 41. It can be seen from this simplified diagram that if a prior art elbow is used in place of the elbows 33, 38, and 39, that poor results may occur in the system. For example, if the pipe length 34 is too short to contain the long straight pipe section suggested in the US. patent to Guise et al., No. 2,708,605, or the remixing venturi suggested in the US. patent to Ortiz, No. 3,144,276, then the streams will not be intermixed downstream of the elbow 33. Therefore, two separate streams, one gas and one dry chemical, will enter the T-joint 35 where the gas stream will be deflected to enter the pipe length 36 and the chemical stream will be deflected to enter the pipe stream 37. If this occurs, only dry chemical will exit from the nozzle 41 and only gas from the nozzle 40.

Alternatively, if the pipe length 34 is suflicient to remix the streams, then the elbows 38 and 39 will again cause stream separation which separation will continue through the nozzles 40 and 41 thereby providing ineffective extinguisher discharge at the nozzles. The present invention, by preventing stream separation in the elbows delivers the required gas-dry chemical mixture through the nozzles 40 and 41 to efiectively extinguish a fire source downstream of the nozzles.

It can therefore be seen from the above that my invention provides a new and improved direction-changing elbow for dry chemical fire extinguisher piping systems which prevents the stream separation of the dry chemical particles and propellant gas in the elbow.

Although I have herein set forth my invention with respect to certain specific principles and details thereof, it will be understood that these may be varied without departing from the spirit and scope of the invention as set forth in the hereunto appended claims.

I claim:'

1. A piping system for uniformly distributing dry chemical fire extinguisher by means of a propellant pressured gas over the surface of a fire comprising: spacedapart discharge nozzles commonly connected to a single chemical source through a piping system incorporating a T-joint therein and direction-changing elbows therein, one of said elbows upstream of said T-joint, said elbow having a venturi interior thereof including a diameter-reducing frusto-conical bore section in the upstream end of the elbow communicating on its downstream end with a constant diameter curved bore, the constant diameter curved bore communicating on its downstream end with a diameter-increasing frusto-conical bore section, said diameterincreasing frusto-conical bore section located in the downstream end of the elbow, said venturi effective to prevent separation of the pressured gas and dry chemical in the elbow, said elbow having internal threads adjacent the ends thereof, the small-diameter end of said diameter-reducing bore section, said constantdiameter bore and the small diameter end of said diameter-increasing bore section having diameters less than the smallest diameter of the threaded portion of the elbow and of the internal diameter of the piping upstream of the elbow.

2. A direction changing pipe elbow having two spaced apart ends disposed at an angle to one another with a curved section intermediate the ends, an internal bore extending from one end to the other through the curved section and open to the ends, means for attaching piping at the ends, said means terminating adjacent the ends, a

venturi interior of the elbow, said venturi including said I bore and a diameter-reducing frusto-conical section adjacent one of the ends, the smaller diameter end of the said frusto-conical section communicating with a constant diameter curved venturi section extending through the curved section, a diameter-increasing frusto-conical bore section adjacent the other of said ends, the small diameter end of the said diameter increasing frusto-conical sect on communicating with the said constant diameter venturi section, the said constant diameter venturi section having a diameter substantially equal to the small diameter ends of the said diameter-increasing and diameter-reducing frusto-conical sections, and the large diameter ends of the said diameter-increasing and diameter-reducing frustoconial bore sections having a diameter equal to or less than the diameter of the bore in the areas of the said means for attaching piping.

3. A piping system for dry chemical fire extinguisher systems having piping sections projecting at an angle from one another and communicating with each other through a curved elbow, one of said sections being upstream of the elbow and the other of said sections being downstream of the elbow, the said upstream section terminating in an externally threaded portion with an internal bore having a first diameter, the said elbow having an internally threaded portion adjacent its upstream end, the externally threaded portion of the section threaded into the internally threaded portion of the elbow, the said elbow having a venturi interior thereof, the said venturi including a diameter-decreasing frusto-conical section adjacent the upstream end thereof, the said diameter-decreasing section having a small diameter end communicating with a constant diameter curved bore, the small diameter end of the diameter-reducing section having a diameter less than the said first diameter of the said piping section, and the constant diameter curved bore having a diameter substantially equal to the small diameter end of the said diameter-reducing section whereby the diameter of the piping system is reduced from the said first diameter of the piping section to the diameter of the curved bore section through the diameter-reducing section, and the constant diameter curved bore section terminating in a diameter-increasing section adjacent the downstream end of the elbow whereby a venturi is provided consisting of the diameter-reducing section, the constant-diameter curved bore section, and the diameterincreasing section.

4. The piping system of claim 3 wherein the downstream end of the elbow has an internally threaded portion adjacent thereto, the said piping section downstream of the elbow having an externally threaded portion threaded into the said internally threaded portion of the downstream end, and the diameter-increasing section having a small diameter end communicating with the constant diameter curved bore section, the said small diameter end of the diameter-increasing section having a diameter less than the diameter of the said internally threaded portion and of the internal diameter of the piping downstream of the elbow.

References Cited UNITED STATES PATENTS 1,475,556 11/1923 Homing 302-64 X 3,144,276 8/ 1964 Ortiz 302-64 2,821,346 1/1958 Fischer 239-336 X FOREIGN PATENTS 720,298 4/ 1942 Germany.

ANDRES H. NIELSEN, Primary Examiner 

